Field of the Invention
The disclosed subject matter of this application is generally related to systems and methods for optimizing batch systems. Particularly, the present application relates to determining whether a batch process is operating in a steady state and generating optimization targets for cycles operating in the same mode of operation.
Description of Related Art
In control systems, control signals are generally applied as inputs to a process. Real time optimization techniques seek to optimize the performance of the process by re-calculating and updating the control signals based at least in part on system performance measurements. For example, in conventional real time optimization processes, certain variables can be sampled at a defined frequency over a predefined period (e.g., one hour). Real time optimization procedures can apply statistical criteria to the sampled data to confirm that the process is operating in steady state, and can compute optimization parameters using various optimization calculation methods. In general, real time optimization is run on a periodic basis, e.g., once every two hours.
Real time optimization techniques can be used in a wide variety of applications including, for example, industrial applications at a refinery. Real time optimization techniques have been applied to a number of traditional refining processes, including crude distillation, hydroprocessing, fluidized catalytic cracking, reforming, and alkylation. Generally, such processes operate in continuous mode and thus do not exhibit significant transient behavior. These processes tend to reach a steady state of operation fairly frequently and therefore can be suitable for conventional real time optimization techniques, which assume a steady state of operation has been achieved.
However, other refining processes also can exhibit significant transient behavior. For example, batch processes tend to exhibit transient behavior when one cycle ends and another cycle begins. For example, in a delayed coker process, transient behavior can be seen when flow is diverted from a first coker drum to a second coker drum and the first coker drum is removed for decoking. Conventional real time optimization techniques can be challenging to implement for batch processes due at least in part to this transient behavior. As such, there remains a need for methods and systems capable of performing real time optimization on batch processes.